A variety of different types of excavation machines have been developed for cutting drifts, tunnels, subterranean roadways and the like in which a rotatable head is mounted on an arm that is in turn movably mounted at a main frame so as to create a desired tunnel cross-sectional profile. WO2012/156841, WO 2012/156842, WO 2010/050872, WO 2012/156884, WO2011/093777, DE 20 2111 050 143 U1. All described apparatus for mill cutting of rock and minerals in which a rotating cutting head forced into contact with the rock face as supported by a movable arm. In particular, WO 2012/156884 describes the cutting end of the machine in which the rotatable heads are capable of being raised and lowered vertically and deflecting in the lateral sideways direction by a small angle in an attempt to try enhance the cutting action.
WO 2014/090589 describes a machine for digging roadways tunnels and the like in which a plurality of cutting heads are movable to dig into the rock face via a pivoting arcuate cutting path. US 2003/0230925 describes a rock excavator having a cutter head mounting a plurality of annular disc cutters suitable to operate in an undercutting mode.
It has been observed that it is particularly challenging to provide the necessary power transmission to the cutter gear while maintaining a compact build. Furthermore, it has been observed that in addition to the high cutting forces needed for the cutter head, in addition to providing sufficient torque, the drive train has to withstand significant axial forces. Still further, it has been observed that it is difficult to supply sufficient quantities of water to the peripheral region of the cutting head without compromising overall build size and complexity of the cutting head and gear.
Furthermore, it has been observed that conventional cutting machines are not optimised to cut hard rock having a strength typically beyond 120 MPa whilst creating a tunnel or subterranean cavity safely and reliably of desired cross-sectional configuration. Accordingly, what is required is a cutting machine that addresses these problems.